Flow injection kinetic spectrophotometric determination of trace amounts of Se(IV) in seawater.

A simple, accurate, sensitive and selective flow injection catalytic kinetic spectrophotometric method for rapid determination of trace amounts of selenium is proposed in this paper. The proposed method is based on the accelerating effect of Se(IV) on the reaction of ethexlenediamine tetrecetic acid disodium salt (EDTA) and sodium nitrate with ammonium iron(II) sulfate hexahydrate in acidic media. The absorbance intensity was registered in this reaction solution at 440nm. The calibration graph is linear in the range of 5x10(-9)-2x10(-7) and 2x10(-7)-2x10(-6)gml(-1). The detection limit is 2x10(-9)gml(-1). The relative standard deviation was 3.4% for 5x10(-8)gml(-1) Se(IV) (n=11), 2.7% for 5x10(-7)gml(-1) Se(IV) (n=11). This method is very simple, rapid and suitable for automatic and continuous analysis. The presented system has been applied successfully to determination of Se(IV) of seawater samples.